The invention relates to a solenoid membrane valve for controlling and/or regulating the flow of liquid media, which valve comprises a membrane fixedly clamped in a valve housing, and an armature frictionally connected with the membrane.
Particularly, in the case of fuel injection systems, it is required to intervene in an automatic control circuit by means which are inexpensive to manufacture, but operate accurately, in order to change the proportions prevailing in the circuit. In a fuel injection system, such change will be in the proportionality of the aspirated amount of air and the injected amount of fuel. This proportionality is changed in dependence on engine data, such as rpm, load, temperature and composition of the exhaust gases, in order to combust the fuel as completely as possible, thereby avoiding or strongly reducing the formation of toxic exhaust gases, while maintaining the greatest possible efficiency of the internal combustion engine and a minimum of fuel consumption. As in the case of many other control systems with similar requirements, it has been found in such automatic fuel injection control systems that liquid is a highly suitable control medium owing to its non-compressibility with preservation of its fluid properties.
Especially when using electrical means for measuring the amount of air or metering the amount of fuel, a solenoid valve is usually an important element of the control system, a magnetically controlled membrane valve having a flat seat being preferred as such element. Apart from the fact that such a valve operates practically free from hysteresis, its flat seat with the cross-sectional area of its annular valve passage produces at short strokes a linear relationship between the stroke of the membrane and the cross-sectional area of the flow passage.